code: def test_no_double_init():
      call_count = [0]
  
      def matvec(v):
          call_count[0] += 1
          return v
  
      # It should call matvec exactly once (in order to determine the
      # operator dtype)
      A = interface.LinearOperator((2, 2), matvec=matvec)
      assert_equal(call_count[0], 1)
  
imports: from __future__ import division, print_function, absolute_import
  from functools import partial
  from itertools import product
  import operator
  import pytest
  from pytest import raises, warns
  from numpy.testing import assert_, assert_equal
  import numpy
  import scipy.sparse
  from scipy.sparse.linalg import interface
  from scipy.sparse.sputils import matrix
label_desc: Use image node_id 8 for calling a global function with example usage: test_no_double_init() and returns: v